1. Field of the Invention.
This invention has relation to a tree harvester useful to harvest felled trees by recovering them from the ground and reducing them to chips. The invention has relation to a method for felling, windrowing, drying and harvesting woody biomass; and to a method of harvesting woody plantations to foster regrowth of multiple stems from single stumps.
2. Description of the Prior Art.
It is known to feed felled tree stems into chipping machines or chippers which convert the tree stems or trunks into chips which can be used as fuel or fiber. Typically, felled trees, and limbs of trees, are physically fed into a chipping machine one tree trunk or stem at a time using an overhead crane and/or a horizontal conveyor to feed the tree into the chipper at a rate that the chipper can handle without it becoming jammed. Usually the felled tree stem is trimmed of branches or "slash" and then transported to the chipper.
Short rotation woody plantations are being grown to rapidly produce wood fiber for many purposes. Such crops are felled and harvested before the tree stems are any larger than about 30 cm at the butt. Felling and trimming is accomplished using hydraulic shears and/or chain saws and this results in leaving stumps anywhere from about 5 cm to 50 cm above the ground. To harvest such woody plantations having tree stems measuring in the neighborhood of 30 cm at the butt is labor intensive, time consuming, difficult and therefore expensive where the chipper can only operate on one stem at a time and/or when the tree stems must be transported to the chipper.
Also, the presence of such stumps extending above the ground prevents uniform and effective replanting and/or subsequent harvesting. The damage done to such stumps when they must be removed by bulldozing or use of other heavy equipment renders the wood fibers therein unusable except for fuel and tends to destroy the root systems preventing sprouting.
Relatively small trees having butts of approximately 30 cm can be felled by using upright tree grapples and shears, but such shears tend to crush the wood fibers and make a significant part of such fibers unuseable for any purpose except fuel or wood pulp.
A rotary rake has been developed to pile up rows of discarded tree parts for burning on forest clear-out sites. This rake is manufactured for and sold by Symonds Australia, Inc. of P.O. Box 10297, Savannah, Ga. 31412. It is illustrated in their undated catalog brochure entitled "SPECIALIZED SITE PREPARATION EQUIPMENT."
What was needed before the present invention was a method and apparatus for felling trees using a slicing shearing action at ground level without appreciable damage to the remaining stumps and root systems or to the wood fibers at the butts of the sheared and felled tree stems. Such apparatus should include a tree harvester which is able to harvest such felled trees as they lie by picking the tree stem butts up off the ground, conveying the tree stems into a chipper as the harvester moves toward the trees, and then discharging the tree chips from the chipper into a vehicle moving with the tree harvester. When a woody plantation has been so harvested, the area should be free from stumps above ground level to facilitate movement of equipment without damage to remaining root systems. Stumps should terminate at ground level to foster regrowth of multiple stems from single stumps.